The present invention relates to a method for the non-destructive testing of a train wheel by means of ultrasound, in particular to a method for the detection of a flaw such as a crack in a region of interest in a train wheel that is rotatable about an axis of rotation. A further subject matter of the present invention is a testing device for the detection of a flaw such as a crack in a region of interest in a train wheel.
A variety of devices and methods for the non-destructive testing of the volume of a test object, such as a train wheel, by means of ultrasound are known according to the prior art. In particular since the introduction of the so-called phased array technique, which is based on the use of a plurality of independently controllable ultrasonic transducers and which permits a specific control of the insonification angle and the focus position of the generated ultrasonic field in the test object by variation of the transmission aperture and the relative phase position of the transmitting transducer elements, a largely automated ultrasound-based material testing, directly in the production process, for example of train wheels, is possible. Generally, pulsed ultrasonic fields are used here, which have a typical repetition rate of a few hundred to a few thousand Hertz and in which the insonified ultrasonic pulses have a center frequency of typically one to about 10 Megahertz.
In connection with the non-destructive testing of train wheels by means of ultrasound, reference is to be made to EP 1 101 105 A1, from which testing methods and devices for train wheels are known that are based on ultrasound and that use the phased array technique. A method is disclosed for detecting a crack in a train wheel which is rotatable about an axis of rotation, wherein an ultrasonic transducer provided for insonifying a first ultrasonic wave is moved relative to the train wheel in a substantially circular manner about the axis of rotation, and wherein the first ultrasonic wave is insonified into the train wheel through the running surface.
Furthermore, another method is disclosed for detecting a crack in a train wheel which is rotatable about an axis of rotation, wherein an ultrasonic transducer provided for insonifying a first ultrasonic wave is moved relative to the train wheel in a substantially circular manner about the axis of rotation, and wherein the first ultrasonic wave is insonified into the hub of the train wheel. Furthermore, devices for carrying out the above-mentioned methods are known from this publication. Here, the phased array technology is used primarily in order to pivot a directed sound beam for sequentially scanning a region of the train wheel to be inspected. Furthermore, the use is disclosed of two-dimensional arrays of ultrasonic transducers, in order to be able to control angular swiveling and focusing in two directions in space orthogonal to each other.
A method for the detection of a flaw in a disk-like or plate-like test object, particularly in a train wheel, is also known. In the test object, an ultrasonic wave that is polarized transversally and parallel to the flat side of the test object is generated on a narrow side of the test object by means of an ultrasonic transmitter and detected after the deflection on the flaw by an ultrasonic receiver spaced from the ultrasonic transmitter. More particularly, the insonification angle of the ultrasonic wave in the test object has a value greater than 10° and less than the refraction angle, which is associated with the first critical angle, of the material from which the train wheel is made. Furthermore, the received signal of the ultrasonic receiver is more particularly evaluated only within a time interval including the time of reception of the ultrasonic wave that is to be expected for the spacing between the ultrasonic transmitter and the ultrasonic receiver and for the insonification angle. The document further discloses a device for carrying out the method.
Regarding the testing tasks for the non-destructive testing of train wheels known to the person skilled in the art from the prior art, reference is made to the entire content of the disclosure of the above-mentioned documents and to the publications regarding the relevant prior art mentioned in these documents. Furthermore, reference is made to the pertinent testing standards, such as, for example, ISO 5948 Railway rolling stock material—Ultrasonic acceptance testing or the internal testing guidelines of Deutsche Bahn No. 907.0403 Zerstörungsfreie Prüfung; Ultraschallprüfung von Radreifen BA 064/065 auf Querrisse in der Bohrungsfläche and der Lauffläche and No. 907.0405 Zerstörungsfreie Prüfung; Ultraschallprüfung der Radkranze von Vollrädern scheibengebremster Radsätze. The content of the disclosure of these prior publications is added in its entirety to the content of the disclosure of the present application by this reference.
Even though the methods and devices known have, by all means, proved their worth in practice in the largely automated testing of train wheels, it was found nevertheless that the time required for the testing is very considerable. It leads to longer downtimes of the rail vehicles to be tested, and thus to considerable financial losses of the operator.